Is Nightshade Vine Poisonous?

Description

• Climbing nightshade is a woody perennial that grows from 6 to 10 feet long, either climbing or trailing along the ground. Its oval pointed leaves can have two basal lobes on larger leaves and are dark green with a purple tinge. The flowers are 1/2 inch wide, star shaped and purple, with the five petals bending backward. The oval, glistening berries are green at first, becoming bright red when ripe. They are juicy, are about 3/8 inch wide and contain numerous light yellow, disc-shaped seeds. Climbing nightshade dies back to the ground in cold winter areas, but in mild winter climates the stems persist year after year.

Toxins

• Climbing nightshade plants contain solanine, a combination of the bitter compound glycoalkaloid and the substance alkamine. Toxins are most concentrated in unripe fruit, with lower amounts present in leaves and stems and less yet in ripe fruits. The concentrations of toxic compounds vary with the growing season and from plant to plant. Humans, wildlife and livestock may be affected by the toxins, and symptoms and severity of the poisoning vary, but it is generally nonfatal, with symptoms of gastrointestinitis, dermatitis and phytophotosensitivity.

Human Toxicity

• To humans, climbing nightshade vegetation and berries do not taste good, which reduces the chance of poisoning. Adults aren't likely to show symptoms unless they eat 10 or more unripe berries, with a fatal dose calculated to be more than 200 unripe berries. The ripe berries are considered mildly poisonous and have little chance of harming children, but children who ingest them are usually conservatively treated with syrup of ipecac. Large doses of solanine can slow the heart, reduce body temperature and cause vertigo, delirium, convulsions and possibly death.

Animal Toxicity

• A number of wild animals regularly eat climbing nightshade as part of their diet. Birds don't seem affected by the toxins, with many species, especially in the Northeast and Southwest U.S., eating the ripe fruit, including crows, eastern kingbirds, thrushes, white-crowned sparrows, waxwings and pheasants. Mammals that eat the fruit include black bear, Virginia opossum, cottontail rabbits and white-tailed deer. Muskrats eat the plant stems. Livestock poisoning occurs in cattle, sheep and horses that graze on the plants. Poisoned cattle exhibited nervousness, rapid pulse and incoordination. Symptoms in poisoned horses were labored breathing, nausea, trembling, constipation and diarrhea, with eventual death possible. Laboratory animals such as mice and hamsters showed poisoning symptoms within 5 to 24 hours when given unripe berries.